Apparatus for magnetic ore-dressing



March 5, 1957 GENZABURO HARADA APPARATUS FOR MAGNETIC ORE-DRESSING Filed Jan. 6, 1951 INVENTOR. GENZABURH Hanan DQ QTTORNEY 2,783,881 APPARATUS FOR MAGNETIC ORE-DRESSING Genzahuro Harada, Yahata-shi, Fukuoka-ken, Japan Application January 6, 1951, Serial No. 204,787 Claims priority, application Japan August 10, 195i) 1 Claim. (Cl. 209-39) Heretofore, various dry or wet systems for ore-dressing have been proposed. Such systems, however, are not suitable for a few special types of ore-dressing. Moreover, according to such known methods, it is very difiicult or evenimpossible to obtain economically and efliciently purified ore of good quality.

The present invention relates to an apparatus for ore dressing.

It is an object of this invention to provide an apparatus which is suitable for all kinds of dry or wet systems of ore-dressing and makes possible the preparation of large amounts of purified ore of good quality, economically and efficiently. The apparatus is especially suitable, for example, for obtaining purified ore of high quality from the gaseous ash of any blast furnace sulphuric acid slag, for efliciently dressing any iron sand, or for manufacturing excellent conglobated ore.

According to the invention selective separation proportional to the magnetism can be effectively and automatically attained by utilizing only the resultant of gravity and magnetic force and also by using any electric source of commercial low voltage current without the necessity of any mechanical moving parts in the main dressing apparatus. Thus, it is possible to obtain, economically and efficiently, a purified ore of very excellent quality.

The nature and advantages of the invention will be more fully understood from the following description and claim and from the accompanying drawings, in which:

Fig. l is a schematic vertical section illustrating an embodiment of the invention.

Fig. 2 is an enlarged schematic vertical section taken at right angles to the section of Fig. 1 and showing in more detail the floating tank illustrated in Fig. 1.

In Fig. 1, the reference numeral 1 is a non-magnetic inclined surface which is made of glass, wood, plastic or rubber. A are electromagnets arranged in series on a common yoke on the inclined surface 1 and these magnets are adapted to be fed from an alternating current source. In this embodiment, commercial current of 100 volts or 200 volts and 50 cycles or 60 cycles, may be used.

As shown in Fig. l, the ore-liquid dressing water tank 9 is divided into two chambers a, b by a vertical wall 26 provided with a slit 27 at its lower edge. Magnetic particles flow out together with the particles of high specific weight through the base opening or openings 28 of the chamber [1, and the light non-magnetic particles regarded as an ore-liquid of low concentration overflow from the upper edge of the overflowing wall 29 of the chamber b or from a conduit tank 30 floating in the chamber b.

When a crude ore-liquid to be treated is charged in chamber a of the apparatus of Fig. 1 through the charging pipe 36, then the particles of high specific weight will form a lower-layer and the particles of low specific weight will form an upper layer and pass into the chamber 11 through the slit 27. In chamber b the particles of high specific weight congregate together in the lower part and the States Patent light particles float in the upper part. In this case, if the electromagnetic apparatus A is excited, then the magnetic particles, even when they are very light, will be attracted towards the lower part and mix with the lower particles of high specific weight. As a result, magnetic dressing and dressing utilizing specific weight can be achieved very readily and the magnetic particles can flow out through the opening 28 as a liquid of high concentration and the light non-magnetic particles can flow out from the upper edge of the overflowing wall 29 as an orcliquid of low concentration. If the concentration of the charged ore-liquid or the level of it varies, then the liquid level of the chamber b will vary and the over-flowing effect at the wall 29 will become non-effective. Such defects may be effectively eliminated by using a floating conduit tank 30 as is shown in Fig. l by broken lines and in detail in Fig. 2 which shows a vertically sectioned elevation of the conduit tank only. This tank 30 consists of a cylinder provided with inlets 33 in its side wall and with several conical chambers 31 connected with several flexible discharge pipes 32 leading to the outside. The tank 3t) is floated in the chamber b by counterweights 35 through pulleys 34.

In the apparatus of Figs. 1 and 2, the magnetic particles are attracted towards the lower part, so the force of gravity and magnetic force can be utilized very effectively and then the total equipment becomes very simple owing to the fact that there is no driving mechanism required. Moreover its treating capacity is very large.

The fine particles of iron sand or ferro-silica of low quality, which may be used as the medium for ore-dressing of heavy liquid or coal dressin are relatively high in their magnetism and specific weight, so that a considerable amount of such material can be recovered by any magnetic dressing apparatus only with a selecting disc. On the other hand, however, a relatively large amount of fine particles of useful iron sand or ferro-silica flows out together with the overflowing liquid or tailing of the selecting disc or magnetic selector. It has been impossible, hitherto, to recover adequately the above-mentioned particles in spite of considerable efforts.

The above defect, according to a further special em bodiment of this invention, can be effectively eliminated by filtrating the heavy liquid which flows out together with the floating ores and precipitated ores from the dressing tank, washing the medium remaining on the surface of the filtrated particles by spraying it, recovering the iron sand 'or ferro-silica from the lower holes as the ore-liquid of high concentration is treated by means of an ore selector utilizing specific weight and magnetism as is described in respect to Figs. 8 and '9, letting the considerable amount of the slime overflow from the upper part, and subjecting the overflowing slime to a floating selection or condensating operation. In this case, however, some amount of slimemingleswith the iron sand or ferro-silica, so that this mingled slime should be extracted by subjecting it again to a selective separation utilizing magnetism and specific weight afteraddition of water to it. After such treatmengif the iron sand or ferro-silica is recycled to the dressing tank afterconcentration, then the viscosity of the heavy-liquid becomes low and its dressing effect hecomes very excellent and loss of the medium used becomes very low.

According-to this invention, as is clear from the above description, any magnetic particles can be effectively and selectively separated.

Furthermore, the method of this invention can be applied very eflectively for selective recovery of any ore contained 'in'the slag of sulphuric acid. The 'slag of sulphuricia'cid produced lay-means of calcinating a pyrite or magnetic pyrite is a very excellent :iron raw material owing to its high content of iron particles. Its use as an iron material, however, has been generally limited, because it contains a large amount of copper and sulphur. On the other hand, it can not be used as a copper raw material owing to its small content of copper. I have found that magnetism of the slag of sulphuric acid varies in accordance with the calcinating degree and if its magnetic particles are crushed into finer particles, then some particles of the material in crushed condition are magnetic and the other particles are non-magnetic and the percentages of copper or sulphur contained in the magnetic particles differ in accordance with the degree of their magnetism. In view of the above facts, according to this invention, eifective separation of the slag of sulphuric acid into a part containing copper and sulphur and into a part containing a very small amount of copper and sulphur was attained by crushing the slag into very fine condition and by separating magnetically and stepwise the crushed particles in accordance with the strength of their magnetism and under variation of the strength of the applied magnetic field. According to such method, the slag can be separated in accordance with its copper or sulphur content, so that it is possible to separate the slag into non-magnetic particles, that is, iron ore containing small amount of copper, and magnetic particles containing a large amount of copper. The latter particles may be easily regenerated to copper ore and iron ore by means of any convenient method. The first table shows an example of magnetic dressing of sulphuric acid slag.

of this invention, after being formed by adding a small amount of water and after completion of its chemical reaction, is mixed with water again and dried, then its hardness becomes stronger.

On the other hand, the particles contained in the tailing of the magnetic dressing in manufacturing the said conglobated ore contain a large amount of coke, hematite, limonite, or quartz particles which are not reduced by calcination. However, the coke particles are relatively coarse owing to their light weight and their porous condition and the hematite and limonite particles are relatively fine and heavy. Although these latter particles form coarse particles by conglomeration owingto the efiect of water contained in the raw ore, they can be easily divided into their original fine particles by pressing them lightly. Thus if the tailing of the magnetic dressing of a gas ash is sieved mechanically after being crushed lightly with a roller, then the coke particles will collect on the sieve, and hematite, limonite, and quartz particles will collect under the sieve. By such method we can separate effectively coke particles and the other iron ore after washing the particles sieved.

The second table shows an example of magnetic dressing of the gas ash of a blast furnace. These data were obtained by dressing magnetically the gas ash of a blast furnace at the Japanese Yahata Company, making the dressed magnetic particles into conglobated ore, and sieving the tailing through a 50 mesh sieve after rolling it with a rubber roll.

These data were obtained by treating sulphuric acid slag Table II at the Tobata Factory of Japanese Yahata Iron Manufacturing Company. The slag was crushed to an under Decmsed 20 mesh size, Weight Total iron quantity T bl 1 (percent) traction due to cale clnation Weight Iron Copper Sulphur Gas ash igg 2g 20 7 70 Percent Percent Percent Percent 25 23 Magnetic part 59. 75 1.04 3. 5 i Non-magnetic part 45 53. 94 0. t6 1. 30

If the method of this invention is applied to the treatment of gas ash from an iron manufacturing blast furnace, then iron ore, coke particles, and melting agent can be eifectively recovered from the gas ash which has been hitherto disregarded. Hematite fractions and limonite fractions contained in the iron ore, that is, in the charging raw ore of any blast furnace are liable to be crushed into very fine particles. Such fine particles of hematite and limonite will be blown out of the furnace together with the gas and will be accumulated at the top of the furnace and at the dust catcher or in the chimney and during their accumulation on their surfaces will be reduced by the reducing gases and high temperature. If such gas ash is separated selectively by the method of this invention, then purified iron ore containing no impurities and having a high quality will be obtained. As these magnetic particles have no impurities, they have an automatic hardening character and are easily formed into a very strong conglobated ore by adding water or by mixing them with fine particles of any other iron ore or scales or lathe scrap of steel. By conglobated ore is meant ore formed into lumps, briquettes, pellets or the like. Such conglobated ore is very firm and also very excellent in its reducing character even when it is exposed to rain water or to high temperature such as 800 C. Its manufacturing cost is very cheap.

Although iron ore may be recovered from gas ash of any blast furnace by means of well-known magnetic separators or any other method and this recovered and purified iron ore has a somewhat automatic hardening character, the conglobating strength and the hardening character of such recovered iron ore are relatively low, because it contains coke particles or other impurities.

If the conglobated ore manufactured by the method The strength of the conglobated ore formed by the purified ore in Table II was over 60 kg./cm. and its mean value of iron content was 58%.

Furthermore, the magnetic ore-dressing method of this invention may be utilized very effectively for selecting only the magnetic iron ore from the hematite, limonite, or pyrite. Naturally, if such ores are so calcinated as to be reduced, then some part of their surfaces becomes ferrous oxide and gains a considerable magnetism with the coexistence of ferric oxide. If such ores are subjected to the dry magnetic dressing of this invention, then we can obtain only the purified magnetic-ore containing no impurities and having high quality and high automatic conglobating character. The chemical combination between such ferrous oxide and ferric oxide in the above purified ore is very unstable and these oxides will easily form iron hydroxide when it is exposed to the air after addition of water. As a result of such chemical reaction, heat is generated and at the same time the original fine particles collect together into a strong conglobated ore. In this case, if it is formed under any pressure, then its particles adhere strongly to each other and its congregating strength becomes especially strong. If the amount of the above water is in excess, then the strength of the conglobated ore after forming is relatively low. On the contrary, if the amount is as little as possible, then hardening will occur in a few minutes and the strength of the conglobated ore after forming becomes very strong even just after forming. As its mechanical treatment is very simple, mass production' of such conglobated ore becomes very easy.

If the conglobated ore is exposed to the air for two or three hours after its formation, then the chemical reaction develops more and more and its temperature goes to about C. and almost all of the first supplied water evaporates and the strength of the conglobated ore becomes considerably greater. If some water is then supplied to the above conglobated ore, then the water Will be absorbed perfectly in a few minutes. After the above treatment, if the ore is exposed to the air for several .ours, then it becomes automatically a conglobated ore of very great strength resulting in the generation of heat and its pressure-resistive force becomes about 100 kg./cm.

As is described, the purified ore obtained by the magnetic dressing of this invention after separation of the calcinated and reduced particles of the gas ash has a sufiiciently automatic hardening character, so that even when it is mixed with any other lathe scrap of iron, other iron ore, and the like it will be possible to make strong conglobated ore by the same method. Such conglobated ore does not become soft and maintains its original rongness even when it is heated to about 200 C.800 C. Thus, the purified ore produced as above described can act as a binder of ores and can make the conglobated ore stronger than the conglobated ore produced by using cement or calcium hydroxide and its hardening time is very short and moreover it does not decrease in quality as does the conglobated ore produced by cement.

Having thus described this invention, I claim as follows:

Apparatus for the separation of ore liquid which comprises, in combination, an ore liquid charging tank having an inclined base, the interior of said tank being divided by a partition Wall into two chambers, said partition being formed with a slit at its lower end for providing communication between said chambers, an outlet formed in said tank at its lowermost portion, and a plurality of alternating current eIectroma-gnets disposed in series along the lower surface of said inclined base.

UNITED STATES PATENTS Carter Apr. 30, Edwards May 28, Bent Apr. 5, Feeley Aug. 15, Isbell July 8, Zander Oct. 7, Weatherby Mar. 13, Bradley Aug. 8, Simpson Sept. 24, Williams Mar. 12, Zuschlag Jan. 21, Zuschlag Mar. 17, Rowand Mar. 9, Scott Feb. 14, Steifensen May 30, Reagan Jan. 5, Rakowsky July 27, Bird Nov. 30, Wuensch Apr. 10, De Vaney Nov. 6, Walker Oct. 21, De Vaney Mar. 6,

FOREIGN PATENTS Sweden July 25,

OTHER REFERENCES Three Phase A. C. in Magnetic Separation, Engr. & Mining Journal; vol. #152, #10, pp. 82, 83 and 118. 

